AT32 USART — 同步模式

Tue, 08 Sep 2026 14:52:21 +0800

USART — 同步模式

固件库: AT32F403A_407_Firmware_Library V2.2.2
芯片: AT32
源文件: AT32/AT32F403A_407_Firmware_Library_V2.2.2/project/at_start_f403a/examples/usart/synchronous/src/main.c

功能简介

本示例演示 USART 串口通信。串口是最基本的通信接口，几乎每个嵌入式项目都会用到。

硬件准备

USB 转串口模块（如 CH340、CP2102）
连接：开发板 TX → 模块 RX，开发板 RX → 模块 TX，共地
电脑端打开串口助手（如 SSCOM、XCOM），波特率与代码一致

完整代码

#include "at32f403a_407_board.h"
#include "at32f403a_407_clock.h"
#define COUNTOF(a)                       (sizeof(a) / sizeof(*(a)))
#define USART2_TX_BUFFER_SIZE            (COUNTOF(usart2_tx_buffer) - 1)
#define SPI2_TX_BUFFER_SIZE              (COUNTOF(spi2_tx_buffer) - 1)
#define DYMMY_BYTE                       0x00

int main(void)
{
  system_clock_config();
  at32_board_init();
  usart_spi_configuration();

  /* wait until end of transmission from usart2 to spi2 */
  while(spi2_rx_counter < usart2_tx_buffer_size)
  {
    /* usart transmit data */
    while(usart_flag_get(USART2, USART_TDBE_FLAG) == RESET);
    usart_data_transmit(USART2, usart2_tx_buffer[usart2_tx_counter++]);

    /* wait until spi receive data */
    while(spi_i2s_flag_get(SPI2, SPI_I2S_RDBF_FLAG) == RESET);
    spi2_rx_buffer[spi2_rx_counter++] = spi_i2s_data_receive(SPI2);

    /* wait until usart receive data, and clear dummy byte in data register */
    while(usart_flag_get(USART2, USART_RDBF_FLAG) == RESET);
    usart_data_receive(USART2);
  }

  /* wait until end of transmission from spi2 to usart2 */
  while(usart2_rx_counter < spi2_tx_buffer_size)
  {
    /* spi put transmit data in data register */
    while(spi_i2s_flag_get(SPI2, SPI_I2S_TDBE_FLAG) == RESET);
    spi_i2s_data_transmit(SPI2, spi2_tx_buffer[spi2_tx_counter++]);

    /* usart transmit a dummy byte to generate clock to slave */
    while(usart_flag_get(USART2, USART_TDBE_FLAG) == RESET);
    usart_data_transmit(USART2, DYMMY_BYTE);

    /* wait until usart receive data */
    while(usart_flag_get(USART2, USART_RDBF_FLAG) == RESET);
    usart2_rx_buffer[usart2_rx_counter++] = usart_data_receive(USART2);
  }

  while(1)
  {
    /* compare data buffer */
    if(buffer_compare(usart2_tx_buffer, spi2_rx_buffer, USART2_TX_BUFFER_SIZE) && \
       buffer_compare(spi2_tx_buffer, usart2_rx_buffer, SPI2_TX_BUFFER_SIZE))
    {
      at32_led_toggle(LED2);
      at32_led_toggle(LED3);
      at32_led_toggle(LED4);
      delay_sec(1);
    }
  }
}

代码讲解

系统时钟初始化：配置 MCU 的主频和时钟树。不同芯片的时钟配置不同，一般由工具生成。

板级初始化：初始化开发板上的 LED、按键等基础外设。

SPI 配置：设置主/从模式、时钟极性（CPOL）、时钟相位（CPHA）、分频系数。主机和从机的 CPOL/CPHA 必须一致。

延时：使用系统延时函数控制 LED 翻转间隔。

实验现象

串口助手收到开发板发送的数据
发送数据后开发板原样返回（回显）

注意事项

串口助手波特率必须与代码一致
检查 TX/RX 是否交叉连接
共地是必须的

GD32 USART — 同步模式

Tue, 08 Sep 2026 14:52:21 +0800

USART — 同步模式

固件库: GD32F30x_Firmware_Library V3.0.3
芯片: GD32
源文件: GD32F30x_Firmware_Library_V3.0.3/Examples/USART/Synchronous/main.c

功能简介

本示例演示 USART 串口通信。串口是最基本的通信接口，几乎每个嵌入式项目都会用到。

硬件准备

USB 转串口模块（如 CH340、CP2102）
连接：开发板 TX → 模块 RX，开发板 RX → 模块 TX，共地
电脑端打开串口助手（如 SSCOM、XCOM），波特率与代码一致

完整代码

#include "gd32f30x.h"
#include "gd32f307c_eval.h"
#include <stdio.h>
#define txbuffer_size1   (countof(txbuffer1) - 1)
#define txbuffer_size2   (countof(txbuffer2) - 1)
#define DYMMY_BYTE       0x00
#define countof(a)       (sizeof(a) / sizeof(*(a)))

void usart_config(void);
void spi_config(void);
void led_init(void);
ErrStatus memory_compare(uint8_t* src, uint8_t* dst, uint16_t length);

/*!
    \brief      main function
    \param[in]  none
    \param[out] none
    \retval     none
*/
int main(void)
{
    /* initialize leds */
    led_init();
    /* turn off LED2~5 */
    gd_eval_led_off(LED2);
    gd_eval_led_off(LED3);
    gd_eval_led_off(LED4);
    gd_eval_led_off(LED5);

    /* configure USART */
    usart_config();

    /* configure SPI */
    spi_config();
    
    while(data_read2--){
        while(RESET == usart_flag_get(USART0, USART_FLAG_TBE)){
        }
        /* write one byte in the USART0 data register */
        usart_data_transmit(USART0, txbuffer1[tx_counter1++]);
        /* wait until end of transmit */
        while(RESET == usart_flag_get(USART0, USART_FLAG_TC)){
        }
        /* wait the byte is entirely received by SPI0 */  
        while(RESET == spi_i2s_flag_get(SPI0, SPI_FLAG_RBNE)){
        }
        /* store the received byte in the rxbuffer2 */
        rxbuffer2[rx_counter2++] = spi_i2s_data_receive(SPI0);
    }

    /* clear the USART0 data register */
    usart_data_receive(USART0);

    while(data_read1--){
        /* wait until end of transmit */
        while(RESET == spi_i2s_flag_get(SPI0, SPI_FLAG_TBE)){
        }
        /* write one byte in the SPI0 transmit data register */
        spi_i2s_data_transmit(SPI0, txbuffer2[tx_counter2++]);

        /* send a dummy byte to generate clock to slave */ 
        usart_data_transmit(USART0, DYMMY_BYTE);
        /* wait until end of transmit */
        while(RESET == usart_flag_get(USART0, USART_FLAG_TC)){
        }
        /* wait the byte is entirely received by USART0 */
        while(RESET == usart_flag_get(USART0, USART_FLAG_RBNE)){
        }
        /* store the received byte in the rxbuffer1 */
        rxbuffer1[rx_counter1++] = usart_data_receive(USART0);
    }
  
    /* check the received data with the send ones */
    state1 = memory_compare(txbuffer1, rxbuffer2, txbuffer_size1);
    state2 = memory_compare(txbuffer2, rxbuffer1, txbuffer_size2);
    
    if(SUCCESS == state1){
        /* if the data transmitted from USART0 and received by SPI0 are the same */
        gd_eval_led_on(LED2);
        gd_eval_led_on(LED4);
    }else{
        /* if the data transmitted from USART0 and received by SPI0 are not the same */
        gd_eval_led_off(LED2);
        gd_eval_led_off(LED4);
    }
    if(SUCCESS == state2){
        /* if the data transmitted from SPI0 and received by USART0 are the same */
        gd_eval_led_on(LED3);
        gd_eval_led_on(LED5);
    }else{
        /* if the data transmitted from SPI0 and received by USART0 are not the same */
        gd_eval_led_off(LED3);
        gd_eval_led_off(LED5);
    }
    while(1){
    }
}

void usart_config(void)
{
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_USART0);
    rcu_periph_clock_enable(RCU_AF);
    /* configure USART Tx as alternate function push-pull */
    gpio_init(GPIOA,GPIO_MODE_AF_PP,GPIO_OSPEED_50MHZ,GPIO_PIN_9|GPIO_PIN_8);
    gpio_init(GPIOA,GPIO_MODE_IN_FLOATING,GPIO_OSPEED_50MHZ,GPIO_PIN_10);
    /* configure USART synchronous mode */
    usart_synchronous_clock_enable(USART0);
    usart_synchronous_clock_config(USART0, USART_CLEN_EN, USART_CPH_2CK, USART_CPL_HIGH);
    
    usart_baudrate_set(USART0, 115200);
    /* configure USART transmitter */
    usart_transmit_config(USART0, USART_TRANSMIT_ENABLE);
    /* configure USART receiver */
    usart_receive_config(USART0, USART_RECEIVE_ENABLE);
    /* enable USART */
    usart_enable(USART0);
}

void spi_config(void)
{
    spi_parameter_struct spi_init_parameter;
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_SPI0);
    rcu_periph_clock_enable(RCU_AF);
    
    spi_i2s_deinit(SPI0);
    
    gpio_init(GPIOA, GPIO_MODE_AF_PP, GPIO_OSPEED_10MHZ, GPIO_PIN_5 | GPIO_PIN_6);
    gpio_init(GPIOA, GPIO_MODE_IN_FLOATING, GPIO_OSPEED_10MHZ, GPIO_PIN_7);
    /* configure SPI0 */
    spi_init_parameter.device_mode = SPI_SLAVE;
    spi_init_parameter.trans_mode = SPI_TRANSMODE_FULLDUPLEX;
    spi_init_parameter.frame_size = SPI_FRAMESIZE_8BIT;
    spi_init_parameter.nss = SPI_NSS_SOFT;
    spi_init_parameter.endian = SPI_ENDIAN_LSB;
    spi_init_parameter.clock_polarity_phase = SPI_CK_PL_HIGH_PH_2EDGE;
    spi_init_parameter.prescale = SPI_PSC_32;
    spi_init(SPI0, &spi_init_parameter);

    /* SPI0 enable */
    spi_enable(SPI0);
}

void led_init(void)
{
    gd_eval_led_init(LED2);
    gd_eval_led_init(LED3);
    gd_eval_led_init(LED4);
    gd_eval_led_init(LED5);
}

代码讲解

GPIO 配置：设置引脚为输出/输入模式，选择推挽/开漏输出，配置上拉/下拉。

SPI 配置：设置主/从模式、时钟极性（CPOL）、时钟相位（CPHA）、分频系数。主机和从机的 CPOL/CPHA 必须一致。

实验现象

串口助手收到开发板发送的数据
发送数据后开发板原样返回（回显）

注意事项

串口助手波特率必须与代码一致
检查 TX/RX 是否交叉连接
共地是必须的

Synchronous on CLing

AT32 USART — 同步模式

USART — 同步模式

功能简介

硬件准备

完整代码

代码讲解

实验现象

注意事项

GD32 USART — 同步模式

USART — 同步模式

功能简介

硬件准备

完整代码

代码讲解

实验现象

注意事项